#include<iostream>
#include<fstream>
#include<cstdlib>
using namespace std;

void file_it(ostream & os,double fo,const double fe[],int n);
const int LIMIT=5;
int main()
{
	ofstream fout;
	const char * fn = "ep-data.txt";
	fout.open(fn);
	if(!fout.is_open())
	{
		cout<<"Can't open "<<fn<<".Bye.\n";
		exit(EXIT_FAILURE);
	}
	double objective;
	cout <<"Enter the focal length of your "
		"telescope objective in mm: ";
		
	cin>>objective;
	double eps[LIMIT];
	cout<<"Enter the focal length, in mm, of "<<LIMIT
		<<" eyepieces:\n";
	for(int i=0;i<LIMIT;i++)
	{
		cout<<"Eyepiece #"<<i+1<<": ";
		cin>>eps[i];
	 } 
	 file_it(fout,objective,eps,LIMIT);
	 file_it(cout,objective,eps,LIMIT);
	 cout<<"Done\n";
	 return 0;
}

void file_it(ostream & os,double fo,const double fe[],int n)
{
	ios_base::fmtflags initial;
	initial=os.setf(ios_base::fixed);
	os.precision(0);
	os.setf(ios::showpoint);
	os.precision(1);
	os.width(12);
	os<<"f.1. eyepiece";
	os.width(15);
	os<<"magnification"<<endl;
	for(int i=0;i<n;i++)
	{
		os.width(12);
		os<<fe[i];
		os.width(15);
		os<<int (fo/fe[i]+0.5)<<endl;
	}
	os.setf(initial);
}
